If you’re constantly stifling desk-side yawns, office environmental factors may be to blame. Try fighting workday fatigue with these adjustments from William Kohler, MD, medical director of the Florida Sleep Institute.

Seek the sun. Natural light is not only an instant pick-me-up, it’s also necessary for regulating your internal clock. If your office doesn’t have a window, try a light box that simulates sunlight.

Jiggle the thermostat. An office that’s too warm may cause drowsiness, while a cold environment can cause tiring restlessness and distraction. The best office temp is 69 to 73 degrees.

Eat for energy. Steer clear of oomph-sapping refined-carb foods like pastries, pasta and baked goods to avoid that midafternoon slump. Instead, opt for a high-protein, low-carb lunch to help sustain alertness.

Tip: Steer clear of those sugary vending-machine snacks to avoid fatigue.